A great way to manage couples and marriages is to use organization contacts, and link people contacts (those who are married to each other) to them. This allows you to create work against them as a couple, such as a joint tax return. 

Here is an example of this:

John and Jane Doe are married. After setting them up as individual people contacts, you can create an organization called John and Jane Doe and link them to that organization. 

Any work items for the couple (like tax work) would be listed under the organization (John and Jane Doe) and any communication related to them as a couple could be tagged to the each individual, that organization, an associated client group and/or the work for them.

Any communications with John will automatically appear on John's timeline, and same goes for Jane.

But if John and Jane were to ever divorce, the people would remain, you would just archive the organization. This way, you will still have access to documents and work associated with it.

Then, let's say John remarries and his new wife’s name is Jillian. You can then create a new organization, to keep track of this new couple.

To represent families, we recommend you use client groups.

Here is an example of this:

If you do taxes for John and Jane Doe as well as their son, Josh, you can capture them as a family by creating a client group called "Doe family" and link all associated contacts to that client group.

At a glance, you will be able to see all members of the Client Group and work that is associated to those members.